The concept of seismic metamaterial has recently gained research interest as an effective way to achieve the seismic protection of buildings and infrastructures. The term metamaterial broadly refers to an engineered material with exotic properties not obtainable in nature, which arise from a tailored design of its structure. Early studies on seismic metamaterials proposed to modify the properties of the soil surrounding the structure to be protected by suitable structuring. In a pioneering work, Brulé and coworkers [1] showed theoretically and via a series of large-scale experimental tests on soft soils that periodic arrangements of vertical boreholes with a spacing of about one meter induce Bragg band gaps for Rayleigh waves at frequencies around 50 Hz. Miniaci et al. [2] later proposed different periodic structures embedded in soil, consisting of cross-shaped, hollow and locally resonant (with rubber, steel and concrete) cylinders to attenuate both Rayleigh and bulk waves in the 1-10 Hz frequency range. On the basis of these works [1,2], many other studies were developed in the last few years [3]. In this study, an innovative concept of resonant metabarrier to control Rayleigh waves propagation in soil is presented. It consists in an array of water tanks embedded in soil, whose resonance associated to sloshing phenomena ensures Rayleigh wave attenuation at very low frequency ranges. The concept is validated by extensive numerical simulations in COMSOL Multiphysics, applying Floquet-Bloch theory on the unit cell to obtain the band structure of the infinite array and computing transmission properties in corresponding 3D finite arrays.